DE102009009528A1 - Pulley with overrunning clutch - Google Patents

Abstract

The invention relates to a pulley with a hub (3) which is fixedly connected to a crankshaft of an internal combustion engine, and a roller body (1) for guiding a belt, which is assigned to a starter drive of the internal combustion engine, wherein the roller body (1) and hub (3 ) via a roller bearing (2) are in contact with each other and via means of an overrunning clutch (5) at a starting operation of the internal combustion engine coupled to each other, after completion of the starting process and at standstill of the starter drive in this case an effective freewheeling action of the overrunning clutch (5) and the roller bearing (2) a relative movement between the roller body (1) and hub (3) is possible, further comprising the means of the one-way clutch (5) in the manner of a wrap spring (6) formed at one end (8) fixed to the roller body (1) is connected and at the starting process to transfer elements (7 a, 7 b) contracts, which between en the roller body (1) and the hub (3) are placed lying in the radial direction and in the contraction of the wrap spring (6) by a contact with the hub (3) and via the wrap spring (6) a frictional connection between the hub ( 3) and the roller body (1) produce.

Description

Field of the invention

The The invention relates to a pulley with a hub, which with a crankshaft of an internal combustion engine is firmly connected, and a roller body for guiding a belt, which is assigned to a starter drive of the internal combustion engine, wherein the roller body and hub via a rolling bearing in contact with each other and via means of a one-way clutch at a starting process of the internal combustion engine coupled together are, after completion of the boot process and at Standstill of the starter drive by an effective freewheel effect the overrunning clutch and the rolling bearing a relative movement between the roller body and hub is possible.

Background of the invention

To the Starting in motor vehicles almost exclusively for Use coming internal combustion engines usually find Starting equipment application, wel che when starting the engine generate the required speed for starting. Usually these launch systems are an electric motor, which when actuated via an engagement relay and a Einspurgetriebe with the crankshaft of the internal combustion engine comes into contact and accelerates to the required speed. For this purpose, a pinion of the starting system, which on the Einspurgetriebe of the starter is located, at the beginning of the starting process einsein and This is done by pressing the contactor moved to the required position.

at moreover, newer vehicle concepts often come this way called start-stop systems for use, by means of which the internal combustion engine switched off when the vehicle is stationary and only for certain actions the driver, such as depressing the clutch pedal, is restarted. These systems are the crankshaft the internal combustion engine permanently with the starter drive, for example via a belt drive in conjunction, said connection with the internal combustion engine running and standing starter drive interrupted by an intermediate one-way clutch is, so a torque transfer only from the starter drive is allowed on the crankshaft.

State of the art

From the EP 1 469 196 A1 a pulley for a starter drive of an internal combustion engine is known, which has a hub fixedly connected to a crankshaft of the internal combustion engine and a roller body. The roller body in this case leads a belt of the starter drive and is in contact with the hub via an intermediate rolling bearing. In addition, means of a one-way clutch are provided between the hub and the roller body, which couple the roller body with the hub during a starting operation of the internal combustion engine and thus enable a torque transmission to the crankshaft. After the start of the internal combustion engine and at standstill of the starter drive, however, a relative movement between the roller body and hub due to the now effective free-wheeling action of the overrunning clutch and the roller bearing is made possible. The means of free-wheeling clutch are formed by spring-loaded rolling elements, which cause coupling either by forming a clamping connection between the roller body and the hub or by rolling allow a relative movement between the two components.

The Execution of a pulley according to the However, the prior art has the disadvantage that for the means of one-way clutch a high space requirement, in particular in the axial direction. Furthermore, there are rolling bearings depending on the embodiment, poorly suited to high speeds above to endure long terms. But this is especially the case a pulley in the starter drive of the case, since the starter drive the most of the time by the freewheeling effect of the overrunning clutch of the Crankshaft is to decouple.

It is therefore the object of the present invention, a pulley for a starter drive an internal combustion engine available to provide, which is designed as compact as possible and In addition, also over a longer period easily high Relative speeds between hub and roller body allows.

Disclosure of the invention

These Task is based on the preamble of the independent claims 1 and 4 in conjunction with their respective characteristic features solved. The subsequent, dependent claims give each advantageous embodiments of the invention again.

According to a first variant, the invention comprises the technical teaching that the means of the overrunning clutch are designed in the manner of a wrap spring, which is connected at one end fixed to the roller body and contracts during the starting process of the internal combustion engine to transmission elements. These transmission elements are in this case placed between the rollers body and the hub lying in the radial direction and provide in the contraction of Schlingfe the by a contact with the hub and the wrap spring a frictional connection between the hub and the roller body ago. By forming the means of the one-way clutch as a wrap, the overrunning clutch can be made very compact, with opening and closing of the overrunning clutch is reliably accomplished depending on the relative speed between the hub and the roller body by a contraction or expansion of the wrap. By providing the transmission elements, the non-positive connection also takes place in the radial direction, which further reduces the space requirement in the axial direction. In addition, the frictional connection is improved by the brake shoe-like acting transmission elements. Furthermore, such an embodiment of a one-way clutch is also easily able to allow higher relative speeds between the hub and the roller body.

In Further development of the invention are the transmission elements each provided with a friction lining on their radial inner sides. This measure can be between the transmission elements and the hub-forming adhesion can be further improved.

According to one advantageous embodiment of the invention are four transmission elements arranged concentrically around the hub lying around. This is done at a contraction of the wrap a very uniform Pressing the transmission elements to the hub.

Corresponding an alternative embodiment comprises the invention the technical teaching that the means of overrunning clutch after Type of leaf spring package formed with at least two leaf springs are, which are equidistant from each other on the outside of a flange-like approach of the roller body are attached and during the starting process due to the centrifugal forces with an inner side of a cup-shaped Anformung the hub in Contact, to this case a positive coupling between hub and roller body produce. through the leaf springs, it is here again possible, please, the overrunning clutch very compact design. By having a connection between the Leaf springs and the inside of the hub only during rotation of the roller body and the associated, acting on the leaf springs centrifugal forces is made, the system is also very low friction and for high relative speeds between hub and roller body suitably trained. Accordingly, the invention carries Pulley with running internal combustion engine only in very small Measures to friction losses, what the overall efficiency improved.

In Further development of the invention are exactly four leaf springs in equidistant Distances to each other on the outside of the flange Attached approach. Advantageously, by such a number of Leaf springs for a compact design of a one-way clutch be realized while at the same time in the non-positive Coupling between hub and roller body on the single leaf spring acting forces reduced to a sustainable level can be.

According to one further advantageous embodiment of the invention the leaf springs at their, with the cup-shaped Anformung in contact with the ends facing the cup-shaped Anformung Each surface provided with a friction lining. This has the advantage that thereby the adhesion between the respective Leaf spring and the cup-shaped Anformung the hub on can be improved.

In Further development of the invention is the rolling bearing of the type trained a ball bearing. By this measure can a low-friction and reliable bearing of the pulley be realized.

Further, The measures improving the invention will be described below together with the description of preferred embodiments of the invention with reference to the figures shown in more detail.

Brief description of the drawings

It shows:

1 a sectional view of the pulley according to the invention according to a first embodiment; and

2 a sectional view of the pulley according to the invention according to a second embodiment.

Detailed description the drawings

In 1 is the pulley according to the invention according to a first embodiment shown in section. This pulley has a roller body 1 , Which leads on its outer diameter a belt of a starter drive of the internal combustion engine, not shown here, and via a roller bearing 2 , which is designed as a ball bearing, with an internal hub 3 is in contact, which in the further course of a screw 4 is firmly connected with a crankshaft, also not shown here, of the internal combustion engine. Between roller body 1 and hub 3 lying and adjacent to the rolling bearing 2 is also an overrunning clutch 5 arranged, which is a wrap 6 , as well as transmission elements 7a and 7b includes. The wrap 6 is here with an end 8th fixed to the inner diameter of the roller body 1 connected and rotates with their turns, the outer diameter of the transmission elements 7a and 7b , The transmission elements 7a and 7b have on their, the hub 3 facing inner sides over here not visible friction linings and are in the radial direction between the hub 3 and the wrap spring 6 versatile.

During a starting process of the internal combustion engine, the roller body 1 rotated about the belt of the starter drive. This is the one end 8th the wrap spring 6 entrained, resulting in a contraction of the wrap 6 around the transmission elements 7a and 7b results, whereupon these with their insides on the hub 3 be pressed. Due to the thereby forming frictional connection between the transmission elements 7a and 7b and the hub 3 becomes the torque of the roller body 1 over the intervening wrap 6 and the transmission elements 7a and 7b on the hub 3 transferred and the crankshaft of the engine dragged over the starter drive. After the start of the engine and at standstill of the starter drive, however, the hub rotates 3 together with the crankshaft faster than the roller body 1 , Through the over the transmission elements 7a and 7b in the wrap 6 initiated direction of rotation widens the wrap 6 on and slips on the transmission elements 7a and 7b by. Consequently, there is no torque transfer from the hub 3 on the roller body 1 and thus the starter drive instead.

In 2 the pulley according to the invention according to a second embodiment is shown in section. In contrast to the variant described in advance has the roller body 1' in this case via a flange-like approach 9 , with which he in a cup-shaped Anformung 10 the hub 3 ' protrudes. Between the radial inside of the flange-like approach 9 and the cup-shaped Anformung 10 is again a rolling bearing 2 provided a relative movement between the roller body 1' and hub 3 ' to enable. On the radial outside of the flange-like approach 9 is a leaf spring package 11 an overrunning clutch 5 ' arranged, which consists of several, fixed to the flange-like approach 9 connected leaf springs, which are at equidistant intervals to each other around the flange-like approach 9 are placed around. Each of these leaf springs of the leaf spring package 11 hereby has one, the cup-shaped Anformung 10 facing side over a friction lining 12 ,

If now the internal combustion engine is started via the starter drive, then the roller body becomes 1' rotated about the belt. This is the leaf spring package 11 moved with, due to the forces acting on the individual leaf springs centrifugal forces radially outward in the direction of the napfförmi gene Anformung 10 the hub 3 ' be moved and with their respective friction lining 12 with the molding 10 contact. Here are the leaf springs of the leaf spring package 11 aligned such that they preferably with their respective ends lagging the cup-shaped Anformung 10 the hub 3 ' to meet. Through this contact becomes the hub 3 ' moved with and thus the crankshaft of the internal combustion engine towed. After the start of the engine and at standstill of the starter drive, the leaf springs of the leaf spring package move 11 due to the no longer effective centrifugal forces again in the direction of the flange-like approach 9 and thus interrupt the contact between the roller body 1' and hub 3 ' ,

1, 1'

Roller body

2

roller bearing

3, 3 '

hub

4

screw

5, 5 '

Overrunning clutch

6

wrap

7a, 7b

transmission elements

8th

The End wrap

9

flange-like Approach roller body

10

cup-shaped Forming hub

11

Leaf spring assembly

12

friction lining

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1469196 A1 [0004]

Claims (8)

Pulley with a hub ( 3 ), which is fixedly connected to a crankshaft of an internal combustion engine, and a roller body ( 1 ) for guiding a belt which is assigned to a starter drive of the internal combustion engine, wherein roller body ( 1 ) and hub ( 3 ) via a roller bearing ( 2 ) are in contact with each other and via means of a one-way clutch ( 5 ) can be coupled to each other during a starting operation of the internal combustion engine, while after completion of the starting process and at standstill of the starter drive by an effective freewheeling effect of the one-way clutch ( 5 ) and the roller bearing ( 2 ) a relative movement between the roller body ( 1 ) and hub ( 3 ) is possible, characterized in that the means of the one-way clutch ( 5 ) in the manner of a wrap ( 6 ) are formed at one end ( 8th ) fixed to the roller body ( 1 ) and is at the startup to transfer elements ( 7a . 7b ), which between the roller body ( 1 ) and the hub ( 3 ) are placed lying in the radial direction and in the contraction of the wrap spring ( 6 ) by contact with the hub ( 3 ) and about the wrap spring ( 6 ) a frictional connection between the hub ( 3 ) and the roller body ( 1 ) produce. Pulley according to claim 1, characterized in that the transmission elements ( 7a . 7b ) are each provided on their radial inner sides with a friction lining. Pulley according to claim 1 or 2, characterized in that four transmission elements concentrically around the hub ( 3 ) are arranged lying around. Pulley with a hub ( 3 ' ), which is fixedly connected to a crankshaft of an internal combustion engine, and a roller body ( 1' ) for guiding a belt which is assigned to a starter drive of the internal combustion engine, wherein roller body ( 1' ) and hub ( 3 ' ) via a roller bearing ( 2 ) are in contact with each other and via means of a one-way clutch ( 5 ' ) can be coupled to each other during a starting operation of the internal combustion engine, while after completion of the starting process and at standstill of the starter drive by an effective freewheeling effect of the one-way clutch ( 5 ' ) and the roller bearing ( 2 ) a relative movement between the roller body ( 1' ) and hub ( 3 ' ) is possible, characterized in that the means in the manner of a leaf spring package ( 11 ) are formed with at least two leaf springs, which at equidistant intervals to each other on the outside of a flange-like approach ( 9 ) of the roller body ( 1' ) are fixed and at startup due to the centrifugal forces acting with an inner side of a cup-shaped Anformung ( 10 ) the hub ( 3 ' ) to make a positive coupling between the hub ( 3 ' ) and roller body ( 1' ). Pulley according to claim 6, characterized in that exactly four leaf springs at equidistant intervals outside of the flange-like approach ( 9 ) are attached. Pulley according to claim 6 or 7, characterized in that the leaf springs at their, with the cup-shaped Anformung ( 10 ) in contact with the cup-shaped Anformung ( 10 ) facing surfaces each with a friction lining ( 12 ) are provided. Pulley according to one of the preceding claims, characterized in that the roller bearing in the manner of a ball bearing ( 2 ) is trained. Internal combustion engine with a starter drive, comprising a pulley according to one of the claims 1-7.